What reportedly happened: The pilot was practicing full-stop landings. He told investigators that he made a “firm” landing and the right main landing gear collapsed. The airplane veered to the right. The pilot could not maintain directional control. The airplane went off the runway and the left main landing gear collapsed. The impact with the ground bent the wings and the fuselage. According to NTSB’s Materials Laboratory report, the right main landing gear strut appeared relatively rough and light gray, consistent with an over-stress fracture of a cast aluminum alloy. The damage was consistent with fatigue.

Probable cause: Fatigue failure of the right main landing gear, rendering directional control impossible and causing an overload failure of the left main landing gear.